In the current study, Nafion is adopted as a dispersant for assisting the water-phase exfoliation of MoS₂. The completely ionized hydrophilic sulfonic groups and hydrophobic polytetrafluoroethylene backbone permit strong non-covalent bonding interactions between Nafion and exfoliated nanosheets for stabilization and functionalization to obtain Nafion–modified MoS₂ (N-MoS₂) nanocomposites. These interactions are stable in different pH environments. The concentration of Nafion influences the exfoliation efficiency and the size of the exfoliated nanosheets. N–MoS₂/Nafion composite membranes are prepared. The N-MoS₂ nanocomposite exhibits good dispersibility in a Nafion matrix, benefitting from the functionalization of Nafion. The N-MoS₂/Nafion composite membrane shows excellent near-infrared light-controllable multi-shape-memory performance with convenient operation. The Nafion-assisted water-phase exfoliation method shows good efficiency, convenient operation, environmental benignity, and broad application potential.